High Plains Drifter

The long-lived, significant tornadic supercell of 31 May 2010 will go down as probably my most thoroughly and successfully documented significant tornadic supercell in my 13 years of storm chasing.  There were three distinct phases of this storm chase, and as such, I will document this account and share my images in 3 parts.  The first phase (Part 1 of 3) was the time frame from roughly 2:45pm to 4:30pm which included a 20-minute tornado southwest of Pritchett, Colorado.  The second phase was a long period from 4:30pm to about 7:00pm when the supercell was non-tornadic but still cycled through several significant occlusions, one of which was very close to being tornadic (Part 2 of 3).  Lastly, the Campo, Colorado significant tornado, the hallmark moment of this supercell, will be documented in Part 3 along with the post-tornado sunset structure as the storm rolled southeast into the Oklahoma Panhandle northeast of Boise City.

Part 2 of 3. 4:30 to 6:55pm CDT (Non-tornadic phase)

(times CDT unless otherwise noted.  numbers in brackets refer to the image number in the embedded image album at the end of this post)

After the south of Pritchett tornado dissipated, the supercell entered a non-tornadic phase, which lasted from roughly 4:30pm until about 7:00pm.  After photographing the tornado, I drove east about a mile and a half then south two miles photographing the storm structure at various points along the way through 4:50pm.  The storm appeared to be taking on a high-precipitation supercell structure with a large mass of precipitation descending from near the main updraft area looking off to the west [1,2,3,4].  I was expecting the storm to approach my location… but it simply wasn’t doing so.  It was moving straight south.  So instead of just sitting there waiting for the storm to approach, I decided to head west again and then drift south.  I sat for awhile at a county road intersection as lightning activity was increasing abruptly.  I set up the tripod with the D200 in hopes of capturing a cloud-to-ground (CG) flash with the storm structure to my west northwest.  I didn’t capture any CG’s, so then I went south.  There is one county road that goes into the far western Oklahoma Panhandle to Black Mesa Park, and I was seriously considering taking this road considering the storm motion straight south… so I made my way south and west through 5:15pm, stopping along County Road 13 about 5 miles north of the Oklahoma border.

I photographed some of the high-based storm structure from here [5] and then drifted back to the north to the road intersection with County Road G where I met up with a group of Canadian storm chasers.  We sat here at this road intersection for a good 10 to 15 minutes or so [6,7,8].  It was at this time that the storm appeared to be making more of a southeast track instead of the due south track it had been taking.  The decision now was to head east back to highway 287 at Campo.  I was in no hurry, though, since the storm was still just crawling at around 5 mph.  At around 5:45 to 5:50pm or so, a high-based rear-flank downdraft clear slot was developing to the north [9].  I drove about three miles east or so and stopped to photograph a new wall cloud to my north-northwest.  This wall cloud in the RFD occlusion was classic [10], and I was preparing for another tornado, setting the tripod up with my D200 zoomed in to about 70mm for some up-close images [11,12].  Right at about 6:00pm, a laminar funnel developed within the tightening wall cloud [14,15,16], making up the tornado cyclone scale rotation.

It came very close to producing a tornado here, and it is quite possible there could have been unseen ground-based rotation beneath the laminar funnel.  I could never confirm a tornado, nor did any other chaser that I know of.  About three or four minutes later, this laminar funnel became a little more stretched out and diagonally oriented [19] as it began to dissipate.  The whole wall cloud area then became wrapped up in rain around 6:10pm [20,21], and I continued east toward Campo.  There were quite a few people from town, including local spotters, watching the storm from the west edge of town on County Road J.

At 6:20pm, I reached Hwy 287/385 and headed south from Campo about 3 miles before stopping along another county road adjacent the highway.  I met up with the College of Dupage group at this location and photographed the structure with some wildflowers to the northwest [23,24,25].  I photographed from this location for about 10 or so minutes before continuing on.  At this point, I was quite content with the chase and decided not to get too cocky in positioning.  It was all about finding the right light at this point since the sun was getting lower.  I didn’t want to shoot into the light to the west.  I took a county road (County Road C) east about a mile or so and found a high spot to shoot from.  There was a fairly well-developed high-based “swirl” marking the new mesocyclone to my northwest [26,27,28].  I sat here for about 10 minutes as well watching this feature approach.  Time was about 6:45 to 6:55pm or so.

With the light pretty harsh to the west, I got tired of shooting to the northwest, so I went back west to Highway 287/385 then south about 1/2 of a mile or so before stopping again along the shoulder of the highway.  Again, up to this point, the chase day was going perfectly, and I was very content with what I have seen up to this point.  Little did I know what I was about to photograph from this very location.  Details of this… the so-called “Campo Tornado”… in Part 3!

The long-lived, significant tornadic supercell of 31 May 2010 will go down as probably my most throroughly and successfully documented significant tornadic supercell in my 13 years of storm chasing.  There were three distinct phases of this storm chase, and as such, I will document this account and share my images in 3 parts.  The first phase (Part 1 of 3) was the time frame from roughly 2:45pm to 4:30pm which included a 20-minute tornado southwest of Pritchett, Colorado.  The second phase was a long period from 4:30pm to about 7:00pm when the supercell was non-tornadic but still cycled through several significant occlusions, one of which was very close to being tornadic (Part 2 of 3).  Lastly, the Campo, Colorado significant tornado, the hallmark moment of this supercell, will be documented in Part 3 along with the post-tornado sunset structure as the storm rolled southeast into the Oklahoma Panhandle northeast of Boise City.

Part 1 of 3. 2:30 to 4:30pm CDT (Pritchett, Colorado tornado)

(times CDT unless otherwise noted.  numbers in brackets refer to the image number in the embedded image album at the end of this post)

I left Dodge City shortly after 11:00am and decided to head toward Springfield, Colorado.  I deliberated for quite awhile… even up until I had to make the turn west of Dodge City… whether to fully commit to the far southeast Colorado target or to head to Lamar first before re-evaluating.  I ultimately decided to take the new South Bypass to get on Hwy 56 and eventually 160 (instead of staying on Hwy 50 to go to Lamar).  Looking at the visible image and seeing the low stratus across southwest Kansas, eastern Oklahoma, and the eastern Texas Panhandle… with clearing to the west — while there was an absence of thin morning stratus farther north — was a clue to stay south (better, deeper moisture).  This was the good kind of morning stratus — the thin stuff the burns off fairly easily by mid-day.  Thin, broken stratus on the western plains is a good sign for late day severe weather when there are southeast surface winds and westerly flow aloft… in late May.

Before I even reached Ulysses, KS, towering cumulus was developing in the target area of far eastern Las Animas County between Kim and Pritchett.  Instead of taking a leisurely stop and eating lunch, I just grabbed some fast-food and continued on my merry way west to Springfield.  I reached Springfield around 1:45pm with a small storm to my west near Pritchett.  The initial storms would develop and dissipate only to reform in the same spot.  After a quick pit stop in Springfield, I continued west on Hwy 160 to Pritchett.  My first stopping point was a couple miles northwest of town on an unpaved county road, where I sat there and watched the genesis of the soon-to-be supercell [1].  I sat there from roughly 2:15 to 2:45pm watching the storm updraft mature to my west a few miles.

Shortly before 3:00pm, I observed the first of two distinct funnel clouds with the initial mesocyclone occlusion looking west from about 4 miles west of Pritchett [2]:

• “persistent well developed funnel cloud about 1/3 to surface from cloud base.  too far away to tell if it was a tornado or not, but it was in the cyclonic shear side of the RFD occlusion… it just dissipated at 1:55pm mdt… lasted a couple minutes”

After that SpotterNetwork report, I drifted south and observed the next funnel cloud [3], with its condensation funnel reaching a bit closer to the surface than its predecessor:

• “another funnel cloud at 2:02pm mountain looking west-northwest from my position… 1/2 way to surface possibly a tornado cannot see debris cloud”

A secondary cell was developing immediately south of the original updraft which was producing the funnel clouds..and its rain core was beginning to come over me while on the unpaved road.  I made it a point not to go very far off of Hwy 160 just in case it started raining… also making sure that the unpaved road I was on was a hard-surface, well-graded road…which it was… so I made my way east a couple miles to Hwy 160 where I continued south.  The time between 3:15 and 3:30pm or so was when the storm was really beginning to blossom with that southern cell now merging with the former cell and essentially taking over.

After a brief bout of nickel size hail and rain, I re-emerged into the inflow sector and was greeted to a nice broadly rotating cloud base lowering to my west.  I noticed Roger Hill’s tour group at the corner on 160 south of Pritchett, and I set up shop probably 1/4 of a mile south of him.  I sat there from 3:30 to 3:45pm or so before continuing south.  In that time, I photographed the storm structure [4,5,6] with, at times, well-developed rotating wall cloud to my west northwest.  Inflow at my back facing the wall cloud was sustained 30-40 mph at times from the east-southeast.  I had to stand in front of my tripod just to make sure it wouldn’t fall over in the inflow.

I drove south a couple miles to County Road U where I then continued east about one mile in order to get a better view of the overall structure of the supercell.  The area of rotation to my northwest a few miles was becoming a little more consolidated [7,8,9] with some semi-transparent precipitation falling in the RFD area of the supercell to the southwest of the wall cloud.  At around 3:58pm, a nice laminar funnel developed [10] from the wall cloud which hovered around a third of the way to the ground.  In a matter of a minute or two, this funnel was likely making ground contact, although I could not confirm this for sure, but the motion in the funnel cloud, the well-established tip of the condensation funnel and the overall organization of the clear slot… all were a pretty good clue that this was likely a tornado.  It was also persistent.  [11,12]

• “looking northwest, fairly stout well developed condensation funnel over 1/2 to the surface from my perspective about 5 S Pritchett”

At 4:03pm, the tip of the condensation funnel reach over halfway to the surface from cloud base [13]…and by 4:04pm, a fairly large triangular-shaped condensation funnel was established.  I photographed both wide-angle (14 to 18mm on the full frame D3) [14,15] to capture the entire structure with the tornado as well as zoomed-in 50 to 70mm on the DX sensor (Nikon D200) to focus on the tornado itself.  Finally, condensation whisps were visible beneath the bowl-shaped condesation funnel at around 4:05pm [16].  At 4:07pm, the tornado was a large bowl-shaped funnel cloud with a small tip condensation funnel with numerous condensation and/or dust whisps looking to the northwest [17].  This then evolved into a more classic truncated cone shape [18,19] with condensation filaments at the tip of the funnel with a small debris cloud beneath at around 4:08pm.  The rear-flank downdraft/occlusion was classic from the southeast vantage point…with a hint of aquamarine color around the occluding tornado cyclone at cloud base [20,21,22].

I called the Pueblo NWS office to give them an update on my observation.  Right as I was making this call, looking off to the west was another very impressive funnel cloud/likely tornado (given the size/laminar shape of the funnel) [25,26].  This was probably 3 or so miles south of the main tornado looking to my northwest.  I believe this was an anticyclonic tornado given its position on the anticyclonic shear side of the rear-flank downdraft.  Shortly after I hung up, I posted another SpotterNetwork report:

• “two tornadoes.  main tornado looking northwest about a mile or two… and another slender tornado to my west.. photographed both in one frame.  main tornado has been periodically on the ground for a number of minutes… perhaps up to 10… it’s a cigar-shaped funnel now with debris whisps observed at times.”

At 4:10pm, the main tornado to the northwest was a vertical cigar-shaped funnel with continued periodic suction spot spin-ups at ground level [29].  I was easily able to capture both tornadoes in one frame with my 14-24mm lens on the D3 [27,28].  The anticyclonic funnel/tornado lasted until about 4:12pm before it finally dissipated.  Meanwhile, the main tornado was still in progress to my northwest.  The entire storm was moving at a snail’s pace, and I was still sitting at the same location as I was 15 minutes prior watching and photographing this entire event unfold.  By 4:15pm, the entire condensation funnel was beginning to shrink and stretch more.  Briefly, the condensation funnel reached all the way to the surface at 4:15pm [31,32,33].  The tornado finally dissipated about a minute or so after that — for a total of just under 20 minutes for this tornado.  After this tornado dissipated, it was time to reposition.

Part 2 of 3 will document the non-tornadic phase of this incredible supercell storm between 4:30pm and 7:00pm — the moments before the Campo tornado.

Marginal supercell storms, high-based, across northeast Colorado.  Taken with point and shoot camera since I didn’t have my Nikon DSLR gear with me as I was coming home from a bowling trip in Reno.